Products > Test Equipment
New EEVblog BM786 Multimeter
<< < (117/133) > >>
tautech:

--- Quote from: Meter Deter on January 10, 2022, 10:43:40 pm ---so let me get this straight. its normal to give false beeps?

for me to avoid false beeps i need to drain the capacitors first?

--- End quote ---
NO !
Beeps represent charge going into caps until the meters continuity threshold is no longer met.

Fast continuity meters have this effect however slow POS continuity won't.
For some meters and bench ones in particular you can adjust thresholds to to not have this behavior however when you want/need best performance you need to reset it again.
EEVblog:

--- Quote from: Meter Deter on January 10, 2022, 10:43:40 pm ---so let me get this straight. its normal to give false beeps?
for me to avoid false beeps i need to drain the capacitors first?

--- End quote ---

Capacitors appear as a short circuit briefly if they are discharged and you apply a voltage to them. If your meter is fast enough and provides enough charge to appear as a low enough resistance then it will beep. That would be expected and normal.
If the capacitor are already charged then that changes the equation and makes it all more complicated.
Brumby:

--- Quote from: EEVblog on January 10, 2022, 10:55:51 pm ---Capacitors appear as a short circuit briefly if they are discharged and you apply a voltage to them. If your meter is fast enough and provides enough charge to appear as a low enough resistance then it will beep. That would be expected and normal.

--- End quote ---

Exactly this.  It's simply the physics involved.

If you want to avoid such "false beeps" you would need the meter to delay the beep until any capacitors involved get a bit of charge in them (from the meter current through the probes) - but how long would you wait?  The time would vary with various values of capacitance.

However, such a delay would annoy the heck out of anyone and everyone I have encountered.  It's not the sort of "feature" that would appeal at all.  (Just witness Dave's reaction when he checks out meters.)

You are far better off having a fast response meter and being aware of the circuitry you are probing to correctly interpret any beeps.  Sometimes all that is required is that you re-check the probing point and/or look at the resistance being displayed.  If it's going up, then you've got capacitance.
EEVblog:

--- Quote from: Brumby on January 11, 2022, 12:32:31 am ---If you want to avoid such "false beeps" you would need the meter to delay the beep until any capacitors involved get a bit of charge in them (from the meter current through the probes) - but how long would you wait?  The time would vary with various values of capacitance.

However, such a delay would annoy the heck out of anyone and everyone I have encountered.  It's not the sort of "feature" that would appeal at all.  (Just witness Dave's reaction when he checks out meters.)

You are far better off having a fast response meter and being aware of the circuitry you are probing to correctly interpret any beeps.  Sometimes all that is required is that you re-check the probing point and/or look at the resistance being displayed.  If it's going up, then you've got capacitance.

--- End quote ---

Yes, it's standard continuity troubleshooting procedure. False negatives (missed connections) are undesirable, that's why people value fast latched continuity modes. If you get a beep you then keep the probes on for longer and read the value and determine if it's a legit connection or a false positive due to a cap or some other in-circuit component.
Having a slow continuity tester and missing beeps can mean it takes way longer to find what you are looking for as you might have to do another entire pass at an even slower rate.

And having such a thing selectable/adjustable might sound like a good solution, but then you have to check it before you start and decide what mode you want (often you won't know unless you start and get some results), and then you also risk forgetting to do that and thinking you are in a mode you aren't.
bdunham7:

--- Quote from: EEVblog on January 11, 2022, 12:57:50 am ---And having such a thing selectable/adjustable might sound like a good solution, but then you have to check it before you start and decide what mode you want (often you won't know unless you start and get some results), and then you also risk forgetting to do that and thinking you are in a mode you aren't.

--- End quote ---

Having the threshold be precise and selectable is very handy, but I'm not feeling any urge to adjust the response time or test current.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod